His first position involved teaching Frenchphonetics and phonemics at the University of California, Los Angeles. After leaving UCLA, Pimsleur went on to faculty positions at the Ohio State University, where he taught French and foreign language education. At the time, the foreign language education program at OSU was the major doctoral program in that field in the U.S. While at Ohio State he created and directed the Listening Center, one of the largest language laboratories in the United States. The center was developed in conjunction with Ohio Bell Telephone and allowed self-paced language study using a series of automated tapes and prompts that were delivered over the telephone.

His research focused on understanding the language acquisition process, especially the learning process of children, who speak a language without knowing its formal structure. The term "organic learning" was applied to that phenomenon. For this, he studied the learning process of groups made of children, adults, and multilingual adults. The result of this research was the Pimsleur language learning system. His many books and articles affected theories of language learning and teaching.[2]

In the period from 1958 to 1966, Pimsleur reviewed previously published studies regarding linguistic and psychological factors involved in language learning. He also conducted several studies independently. This led to the publication in 1963 of a coauthored monograph, Underachievement in Foreign Language Learning, which was published by the Modern Language Association of America.

Through this research, he identified three factors that could be measured to calculate language learning aptitude: verbal intelligence, auditory ability, and motivation. Pimsleur and his associates developed the Pimsleur Language Aptitude Battery (PLAB) based on these three factors to assess language aptitude. He was one of the first foreign language educators to show an interest in students who have difficulty in learning a foreign language while doing well in other subjects. Today, the PLAB is used to determine the language-learning aptitude, or even a language-learning disability, among secondary-school students.

In 2006, Pimsleur's daughter, Julia Pimsleur, created the Entertainment Immersion Method® inspired by the Pimsleur Method, which is the foundation of the Little Pim language teaching program for young children, sold in the U.S. and 22 countries. [5]

In 2013, Simon & Schuster reissued Dr. Paul Pimsleur's out-of-print book How to Learn a Foreign Language[6] in hardcover and eBook format to celebrate the 50th anniversary of Paul Pimsleur's first course.

Pimsleur, Paul; Quinn, Terence (editors). The psychology of second language learning: papers from the Second International Congress of Applied Linguistics, Cambridge, 8–12 September 1969. London, Cambridge University Press, 1971. ISBN0521082366

Poems make pictures; pictures make poems. Poems by Giose Rimanelli and Paul Pimsleur. New York : Pantheon Books. 1972. ISBN0394923871